Dear Lifehacker,I have a simple question: does speeding really get you to your destination any faster? I tend to be a more conservative driver and it drives my boyfriend crazy (who always goes 10mph over the speed limit. I'm pretty sure that between red lights and traffic, there's not enough time saved for it to even matter. Which one of us is right?

Sincerely,Drive Smarter, Not Faster

Dear Smarter,Well, the first thing to establish if you're trying to figure out whether or not speeding is worth it is the legal cost. Even if we could prove that speeding is a more efficient way to get from one place to another, it's illegal and fines could cost hundreds of dollars. Not to mention the increased chance of getting into a car accident. For the safety of everyone on the road, keep the possible consequences in mind while driving.

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That being said, we won't pretend that speeding isn't a pretty common occurrence. In most states, you can get away with less than 10mph over the speed limit. For reference sake, we'll take a look at how much an extra 10mph can help.

Mathematically, Speeding Only Helps On Long Car Trips

Before we account for traffic lights, other drivers, or delays, let's examine some basic math. We'll look at a few different length trips—say, 15, 30, 50, and 500 miles—and at several different speeds. This chart shows how long each trip would take at the speed limit, how long it would take at 10 mph over it, and how much time you save by speeding:

As you can see, unless you're going on a really long car trip, the time savings for speeding are already pretty minimal. The most time saved on a trip shorter than 500 miles is about 12 minutes (Trip G above). However, that's on a trip that's already an hour long. Factor in traffic lights and congestion (which we'll get to in a bit) and those savings can disappear quickly.

What's more fascinating is that the higher the speed limit is already, the less time you save by exceeding it, not more. This might seem counter intuitive. However, the faster you're traveling to start with, the more you have to exceed the speed limit to achieve the same proportionate increase. If the speed limit is 35 mph and you're going 45 mph, you're traveling nearly 30% faster than the speed limit. If the speed limit is 65 mph and you're going 75 mph, that's only about a 15% increase.

Ironically, the one situation in which speeding results in any substantial gains—during a long car trip on high speed freeways—is when mild speeding helps the least. Obviously you can increase those time savings by traveling even faster, but once you break the speed limit by more than 10 mph, you lose the indulgence of most law enforcement officers. This is a bad idea across the board.

Almost All Theoretical Gains are Lost In Traffic

Math is fun and all, but it's not that indicative of real life. During high traffic hours or in heavily populated areas, the hypothetical time savings go out the window. For starters, you can't maintain any constant speed, much less one that exceeds what everyone else is traveling at. Every time you stop at a traffic light you lose gains as your vehicle slows down approaching the intersection, while you wait for the light to turn green, and while you accelerate back up to speed again.

Once again revisiting Trip G in the chart above, let's assume that over the course of that 50 mile trip, you encounter 25 traffic lights (or one every two miles), each with the potential for an average 30-45 second wait time. This means the potential time lost at red lights is anywhere between 12.5 to 18.75 minutes. Now, you'll face these delays regardless of how fast you travel in between the lights. In the Trip G example, speeding will, at best, counteract the losses at red lights, and at worst, those red lights will cut your 12 minute savings down to about 6 minutes on a 50 mile trip that's already taking over an hour.

Even if you make the argument that a 50 mile trip would take place mostly on the freeway, that doesn't help us. As we established earlier, speeding doesn't help freeway driving nearly as much. The difference between Trip G (at 45 mph) and Trip I (at 65 mph) above is a six minute savings loss. Even without the lights, you still lost half your savings. And let's be real, on a 50 mile trip, it's still pretty likely you're going to encounter a couple (dozen) traffic lights along the way.

To put all these savings of a few minutes into perspective, let's assume the average speeding ticket cost is $150. In order for six minutes of your time to be worth $150, you would have to make $1,500/hour or about $3,000,000 per year.

Now, obviously, the number of red lights you'll encounter, the length of time you'll spend at each, and the density of traffic will vary widely by your area. In some cities, you could travel a full 50 miles without encountering a single traffic light. In others, you'll pass through 25 signals every two miles. However, this only emphasizes the point: your speed is only one of the factors that you'll encounter while driving and many of the things that determine how long your trip takes are out of your control.

There Are a Few Things That Can Help

We can more or less conclude that speeding only saves you a marginal amount of time, if it saves any at all. However, there are still a few things you can do to drive more efficiently that actually helps and doesn't risk getting in trouble with law enforcement or an accident:

Plan out multi-stop trips efficiently: If you're planning to hit up more than one location, the best thing you can do is to plan the most efficient route before you leave. There's no perfect way to do this (and, in fact, this is the subject of a notable logistics problem), but even a little extra forethought can prevent backtracking, which will save far more time than speeding.

Avoid left turns: While you're planning out your route, or if you simply come across the choice while you're out, choosing a right turn instead of a left one will not only save time, but gas as well. This doesn't mean you have to ban left turns entirely in favor of ridiculous right turn schemes, but if you're choosing between two gas stations on opposite sides of the road, the one on the right will take less time to get to.

Prefer roundabouts when available: Roundabout-style intersections may not be very common in the United States, but in the rare event that you can choose between a route that contains a four-way stop and a roundabout, the roundabout will be a more efficient system of coordinating traffic. All other things being equal, of course.

Of course, the best way to get your destination sooner is to leave earlier. That advice may be trite and impractical at times—everyone runs late occasionally—but leaving your home ten minutes earlier is a much more reliable way to save time and comes with considerably fewer risks.